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Title: MAJOR GALAXY MERGERS ONLY TRIGGER THE MOST LUMINOUS ACTIVE GALACTIC NUCLEI

Abstract

Using multiwavelength surveys of active galactic nuclei (AGNs) across a wide range of bolometric luminosities (10{sup 43} < L{sub bol} (erg s{sup -1}) <5 Multiplication-Sign 10{sup 46}) and redshifts (0 < z < 3), we find a strong, redshift-independent correlation between the AGN luminosity and the fraction of host galaxies undergoing a major merger. That is, only the most luminous AGN phases are connected to major mergers, while less luminous AGNs appear to be driven by secular processes. Combining this trend with AGN luminosity functions to assess the overall cosmic growth of black holes, we find that {approx}50% by mass is associated with major mergers, while only 10% of AGNs by number, the most luminous, are connected to these violent events. Our results suggest that to reach the highest AGN luminosities-where the most massive black holes accreted the bulk of their mass-a major merger appears to be required. The luminosity dependence of the fraction of AGNs triggered by major mergers can successfully explain why the observed scatter in the M-{sigma} relation for elliptical galaxies is significantly lower than in spirals. The lack of a significant redshift dependence of the L{sub bol}-f{sub merger} relation suggests that downsizing, i.e., the general declinemore » in AGN and star formation activity with decreasing redshift, is driven by a decline in the frequency of major mergers combined with a decrease in the availability of gas at lower redshifts.« less

Authors:
 [1]; ; ;  [2]
  1. Departamento de Astronomia, Universidad de Concepcion, Casilla 160-C, Concepcion (Chile)
  2. Yale Center for Astronomy and Astrophysics, P.O. Box 208121, New Haven, CT 06520 (United States)
Publication Date:
OSTI Identifier:
22078477
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal Letters
Additional Journal Information:
Journal Volume: 758; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 2041-8205
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BLACK HOLES; BOLOMETERS; GALAXY NUCLEI; LUMINOSITY; MASS; RED SHIFT; STARS

Citation Formats

Treister, E., Schawinski, K., Urry, C. M., and Simmons, B. D., E-mail: etreiste@astro-udec.cl. MAJOR GALAXY MERGERS ONLY TRIGGER THE MOST LUMINOUS ACTIVE GALACTIC NUCLEI. United States: N. p., 2012. Web. doi:10.1088/2041-8205/758/2/L39.
Treister, E., Schawinski, K., Urry, C. M., & Simmons, B. D., E-mail: etreiste@astro-udec.cl. MAJOR GALAXY MERGERS ONLY TRIGGER THE MOST LUMINOUS ACTIVE GALACTIC NUCLEI. United States. doi:10.1088/2041-8205/758/2/L39.
Treister, E., Schawinski, K., Urry, C. M., and Simmons, B. D., E-mail: etreiste@astro-udec.cl. Sat . "MAJOR GALAXY MERGERS ONLY TRIGGER THE MOST LUMINOUS ACTIVE GALACTIC NUCLEI". United States. doi:10.1088/2041-8205/758/2/L39.
@article{osti_22078477,
title = {MAJOR GALAXY MERGERS ONLY TRIGGER THE MOST LUMINOUS ACTIVE GALACTIC NUCLEI},
author = {Treister, E. and Schawinski, K. and Urry, C. M. and Simmons, B. D., E-mail: etreiste@astro-udec.cl},
abstractNote = {Using multiwavelength surveys of active galactic nuclei (AGNs) across a wide range of bolometric luminosities (10{sup 43} < L{sub bol} (erg s{sup -1}) <5 Multiplication-Sign 10{sup 46}) and redshifts (0 < z < 3), we find a strong, redshift-independent correlation between the AGN luminosity and the fraction of host galaxies undergoing a major merger. That is, only the most luminous AGN phases are connected to major mergers, while less luminous AGNs appear to be driven by secular processes. Combining this trend with AGN luminosity functions to assess the overall cosmic growth of black holes, we find that {approx}50% by mass is associated with major mergers, while only 10% of AGNs by number, the most luminous, are connected to these violent events. Our results suggest that to reach the highest AGN luminosities-where the most massive black holes accreted the bulk of their mass-a major merger appears to be required. The luminosity dependence of the fraction of AGNs triggered by major mergers can successfully explain why the observed scatter in the M-{sigma} relation for elliptical galaxies is significantly lower than in spirals. The lack of a significant redshift dependence of the L{sub bol}-f{sub merger} relation suggests that downsizing, i.e., the general decline in AGN and star formation activity with decreasing redshift, is driven by a decline in the frequency of major mergers combined with a decrease in the availability of gas at lower redshifts.},
doi = {10.1088/2041-8205/758/2/L39},
journal = {Astrophysical Journal Letters},
issn = {2041-8205},
number = 2,
volume = 758,
place = {United States},
year = {2012},
month = {10}
}